Granular-bed filter.



No. 630,063. Patented Aug. 1,1899.

J. A. MAIGNEN.

GRANULAR BED FILTER.

(Application filed Nov. 12, 1898. Renewed July 1, was.

(No Model.)

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' UNrrnn STATES PATENT OFFICE.

JEAN A. HAIGNEN, OF PHILADELPHIA, PENNSYLVANIA.

GRANULAR-BED FILTER.

SPECIFICATION forming art of Letters Patent No. 630,063, dated August 1,1899.

Application filed November 12, 1898. Renewed July 1,1899. Serial No.722,586. (No model.)

To all whom, it nuw (saucer/t:

Be it known that I, JEAN A. MAIGNEN, of Philadelphia, in the State ofPennsylvania, have invented certain new and useful Improvements in theFormation of Granular- Bed Filters, whereof the following is aspecification, reference being had to the accompanying drawings.

My invention relates particularly to filters wherein the flow of thewater is downward through a granular bed, at the upper surface of whichthe initial separation of the impurities from the water is effected. Tosecure the maximum efficiency at all points in the area of a filter ofthe aforesaid type, it is obviously essential that the water beuniformly distributed to gravitate uniformly throughout said area. Itiswell known that to secure such uniformity of operation it is necessarythat the upper surface of the granular bed should occupy an absolutelyhorizontal plane, for any irregularities in said surface through whichthe water is introduced to'the granular mass induces irregularities inthe rate of flow through said mass in correspondence with theirregularities of said surface and the flow of water initiatedirregularly tends to persist and form conduits through the mass for thepassage of the water without filtration. Such irregw laraction of thefilter thus induced by the mere inequalities of the surface aforesaid issubsquently supplemented by the consequent irregular deposit of mud andother freely suspended matter in the hollows of said surface, while theelevations thereof remain comparatively bare. An irregular upper surfaceupon a filter of the type specified is therefore so detrimental to itsefficiency of operation that the text-books upon the subject lay stressupon the importance of obliterating even such small depressions asfoot-prints from a granular bed comprising several acres of top surface.

Ordinarily in the formation of a filter-bed of the class specified itsupper surface is leveled by the usual surveying methods, marks beingestablished upon the embankments, from which lines are projected fromside to side in both directions, and workmen are employed to reduce thesurface to a horizontal plane to correspond with said lines while thegranular material is in a dry state.

Said leveling operation, being not only neces saryin the primaryformation of a filter, but upon each subsequent occasion when thefilter-bed is cleansed by the removal of the membrane of mud or othersuspended mate rial deposited thereon, is an important factor in theexpense of maintenance of the filter.

My present invention consists in a simplified method of determining thehorizontal plane to which the upper surface of a granular-bed filtermust be reduced and in the re duction of such surface to a horizontalplane while said mass is submerged in water.

Figures 1 and 2 of the drawings diagrammatically illustrate steps in myprocess.

As shown in Fig. 1 of the drawings, the granular mass of filteringmaterial A being deposited within the retaining-Walls B the uppersurface a of said mass is of course primarily irregular, as indicated.Water is then flowed within the mass, which is saturated therewith untilthe free plane surfacea: of the water is above the general level of theirregular surface a. Said surface ais then reduced to parallelism withthe surface as of the Water, as indicated in Fig. 2, and the massA isthen ready for operation as a filter. Said process of formation is ofcourse the same whether the mass isto be primarily formed or re-formedsubsequent to the removal of the accumulated deposit upon its surface.

My improved process is not only advantageous in. that an absolutelyhorizontal plane is established without cost of surveying, &c. but afurther advantage consists in that whereas in the ordinary process offormation the level surface is established with the granular material ina dry state and is therefore more or less disturbed by the subsequentinflux of water by my improved method of formation the mass of materialis primarily saturated, and when leveled so remains.

It is obviously not of the essence of my invention for the Water-level wto be established with respect to the surface a of the granular bed inthe precise relation which I have illustrated. It is, however, essentialthat said water-level be so established as to be comparable with thesurface of the granular mass at any point therein and the horizontalplane of the latter be thereby determined. I therefore do not desire tolimit myself to the precise relation of the planes which I have shown.It is, moreover, to be understood thatI have used the term water hereinin a descriptive and'not in a restrictive sense, as it is obvious thatthe precise nature of the liquid filtered is not of the essence of myinvention. V

'I claim- The hereinbefore-described process of formation ofgranular-bed filters, consisting in saturating a mass of granularmaterial with water until a horizontal plane of said Water isestablished, in such relation with said mass as to becomparable with theupper surface of the latter, and reducing the uppersurface of said massto parallelism with the plane surface of said Water, substantially asand for the purpose set forth.

JEAN A. MAIGNEN. l/Vitnessesz EDWARD EVERITT, ARTHUR E. PAIGE.

